Two dimensional arrays of such electronic devices as Vertical Cavity Surface Emitting lasers (VCSELs) or Light Emitting Diodes (LEDs), have numerous applications in high capacity switching systems, back-plane computer interconnect technology, smart pixel arrays, high power coherent beam generation, and two dimensional beam steering. The elements of these arrays can either work in unison to generate coherent supermodes or operate independently as high density sources for multi-channel systems. In the manufacture of such electronic devices, an area of semiconductor layers, such as distributed Bragg reflector mirror and/or confining layer, above an active (radiation emitting) region is peripherally implanted with dopant (proton) ions while leaving the central area of those layers unaffected. These peripheral areas become impenetrable to electric current restricting its passage to the central area of the active region. In this manner the electric current flow from a top electrode to a bottom electrode of the device is directed through the central area of the active layer defined by the so-formed window, while the optical radiation is emitted through the window and then through the aperture in the top electrode. Examples of VCSELs are disclosed in articles by G. Hasnain et al., "High Temperature and High Frequency Performance of Gain-Guided Surface Emitting Laser," Electronics Letters Vol. 27, No. 11, May 23, 1991, pp. 915-16, and G. Hasnain et al., "Performance of Gain-Guided Surface Emitting Lasers with Semiconductor Distributed Bragg Reflectors", IEEE Journal of Quantum Electronics, Vol. 27, No. 6, June 1991, pp. 1377-85.
Applicants have discovered that conventional photoresist processing of masks for ion implantation and subsequent implantation of proton ions through the masks leads to improperly defined windows, wherein the walls of the windows have unsharply defined, fuzzy implantation damage outlines resulting in higher device resistance. This leads to higher threshold values of the device, which leads to lower operating characteristics of the device. Thus, it is desirable to produce implantation damage profile which more precisely defines the window in the ion-damaged area.